1. Field of the Invention
Embodiments of the invention relate to an organic light emitting diode (OLED) display device and a method for driving the same, which avoid display failure caused by flicker or glare occurring when an operation mode of the OLED display device is changed to an idle mode under the condition that the OLED display device is applied to a mobile communication device such as a smartphone or a tablet computer, thereby being capable of achieving an enhancement in reliability.
2. Discussion of the Related Art
As flat panel display devices that have recently been highlighted, there are a liquid crystal display (LCD) device, a field emission display (FED) device, a plasma display panel (PDP) device, an organic light emitting diode (OLED) display device, etc. Among such flat panel display devices, the OLED display device is a self-luminous device in which an organic light emitting layer emits light through re-combination of electrons and holes. Since the OLED display device exhibits high brightness, and employs a low drive voltage while having an ultra-slim structure, it is expected to be a next-generation display device.
Such an OLED display device includes a plurality of unit pixels, each of which includes an OLED constituted by an anode, a cathode, and an organic light emitting layer interposed between the anode and the cathode, and a pixel circuit for independently driving the OLED.
The OLED display device is usefully applied to mobile communication devices such as smartphones or tablet computers because OLED display device exhibits high brightness, and employs a low drive voltage while having an ultra-slim structure.
Recently, for transmission of image signals or control signals, a command communication protocol such as mobile industry processor interface (MIPI) interface protocol has been applied to the mobile communication devices. In some instances, it has also been required to employ a command communication protocol for an idle mode (for example, a partial idle mode) requiring low-consumption of electric power. In other words, in an idle mode, in which only basic information such as information as to current time or weather is displayed to allow the user to identify the displayed information, various matters should be taken into consideration, differently than an image display mode, in which an image, etc., are displayed at a user's request.
For example, in the instance of an LCD device, it may be possible to simply implement an idle mode requiring low consumption of electric power, simply by turning a backlight off. On the other hand, in the instance of an OLED display device, a driving system for driving the OLED display device at a lowered drive voltage or at a lowered drive frequency was employed because the OLED display device is a self-luminous display device. However, when the OLED display device is driven at a lowered drive frequency, the blank period, in which no image is displayed, is lengthened because driving control signals are frequency-modulated in proportion to the drive frequency. As a result, there is a problem in that the blank period is recognized by the naked eye. When the OLED display device is driven using a variable drive voltage, there may be a problem of irregular mode change driving timing because capacities of a capacitor and resistors employed in the display device are fixed.
In other words, each of the capacitor and resistors of a feedback circuit employed for stabilization of a drive current and a drive voltage from a power IC is set to have an optimal capacity in order to avoid abnormal current variation or the like. However, when variation in current amount and voltage level occur during mode change to an idle mode or an image display mode, the drive current and drive voltage from the power IC exhibit different driving start timings for respective modes in accordance with respective fixed capacities of the capacitor and resistors. In this instance, display failure caused by flicker or glare may occur. Due to such a display failure, there may be a degradation in reliability or other problems.